Raphael josia



UNITE STATES PATENT EETCE,

RAPHAEL JOSIA, ()F FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND I C. DE VARIGNY, OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES OF LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,513, dated October 3,1882.

Application filed August 9, 1882. (No spcciniens.)

To all whom it may concern Be it known that I, RAPHAEL JOSIA, of Florence, Kingdom of Italy, have invented or discovered a new and uselul Improvement in Gompositions for Treating Sulphates of Lime for the Manufacture ofArtificial Marble; and I do hereby declare the following to be a lull, clear, concise, and exact description thereof.

In an application for Letters Patent of the United States filed March 2, 1882, I have described and made claim to an improved process of treating or preparing gypsum (calcie sulphate or sulphate of lime) in the making of articles of a material which I have termed eertaldite without pulverization of the gypsum.

In said application I described briefly certain of the compounds or compositions which I employ to produce certain effects and the manner "of using them, but stated that separate applications would be made for patents for such compositions.

The present applTcation relates to one of the compositions so referred to, and it is designed for use in the process herein described in the making of dark-blue certaldite.

In carrying out the process referred to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such,by the use of suitable well known tools. The gypsum employed may be the ordinary native gypsum otlcommerce, though I prefer that which is comparatively pure or free from other matters of different composition. Such gypsum is usually obtained bydrated, or containing a certain percentage of water in its composition; and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the whole of such water. This is done by subjecting it to the action of a graduallyincreasing heat, varying by preference with the size and quality of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration is obtained. The length of time as well as the degree of heat required to efiect this result will vary somewhat with the size, character, and purity of the gypsum employed; but the temperature should not exceed 500 Fahrenheit, and both it and the time of exposure should be regulated and limited with reference to securing uniformity of treatment throughout the whole mass or body. This operation may be known to be complete when a fracture of a test block preseats a uniform white color. Any suitable drying or bakingapparatus may be employed for this purpose, many such being known in kindred branches of the arts; but it should be of such construction that the material under treatment shall not be brought into direct contact with the fire. When the desired dehydration has been effected the furnace is allowed to cool-gradually, in order that the material under treatment maybe cooled gradually; or the material may be removed, with due care to prevent breaking and exposure to moisture, and allowed to cool outside of the furnace gradually until it is reduced in temperature sufficiently to permit handling 76 with safety in its subsequent treatment, which is designed to impart to it the desired color or tint and a high degree of insolubility and hardness throughoutits mass. This step involves the use of the composition which forms the subject-matter of invention in the present application. This composition is formed of the following elements: water, by weight, two hundred parts, alum, by weight, four to five parts; oxalic acid, by weight, two to two and 80 a half parts; aniline-blue, (dark,) by weight, one part; sulphuric acid, by weight, five-tenths part. These ingredients, being mixed in about the proportions named, form a solution which is used as a bath, and to this end a suitable quantity of it is placed in a vessel of proper shape to receive the article to be treated, which is dipped or immersed in the bath and subjected to its action until the article has acquired the desired degree of hardness and color. 0 The length of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or solution, the porosity and nature or physical and chemical condition of the article, but usually twelve 5 hours (more or less) will suffice, though to secure uniformity of treatment and of result through the whole body or mass of the article I prefer repeated dippi ngs-two, three,or moresay two or three seconds at first, and increasing gradually to one, two, three, or more minutes, more or less, with drying intervals of like increasing length between dippings,for half or three-quarters of an hour or so, after which the article may remain in the bath for twelve hours or so. 7

While I do not limit my invention to any particular theory of chemical or physical reactions involved in the use of this bath as above described, I believe, with my present knowledge, that thesalt (alum) held in solution, by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the calcic sulphate, and renders it more compact, harder, and less soluble, and that the oxalic acid of the bath acts chemically or physically upon the impurities or matters of other composition, (carbonates, &c.,) which are usually contained in greater or less quantities in native gypsums, and produce a like indurating effect upon them. Though the salt may have an induratingaction upon the impurities present, and the acid may act in like manner more orless upon the calcic sulphate, the sulphuric acid is employed as a solvent of the anilineblue, which is preferably of the brand or kind known in Europe as B B B, and gives the desired dark-blue color to the calcic sulphate. This color will usually be variegated more or less, however, with irregular lines, veins, or markings of othershades'or tints, due probably to impurities present in the gypsum. A highlyornamental and beauti fully-variegated darkhlue color is thus given to the article, (certaldite,) as well as such a degree of hardness, insolubility, and susceptibility of taking a high polish as renders it an excellent substitute for marbles, ornamental stones, tiles, 850., in the various uses to which they are applied in the arts.

\Vhen the article has been treated in the bath as above described it is removed and dried by exposure to the sun or to an equivalent furnace-heat for one or two hours, or by ordinary atmospheric exposure for two or three days, when it is ready for polishing and such other manipulation as may best fit it for its intended use, which may be done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications of the same, as circumstances may require, forms the subjectmatter of the first application herein referred to. Neither do I limit my present invention to the particular way herein described of applying it, though I now believe this way or process to be the best. I also believe the proportions ofingredients which I havenamed in forming my improved composition to be the best for the purposes stated, and among others to secure a uniform degree of hardness and color throughout the mass of the article. It the solution be very strong, there is great danger of rendering the surface of the article hard very quickly, and thereby preventing proper action of the bath upon the interior substances of the article; or, if the solution be very weak too much time is required, and even then a proper degree of hardness, density, and insolubility is not secured also, by the conjoint action of all the elements of the bath much better results are secured, especially upon native gypsums, than by a solution formed of a part of the elements. For these reasons I prefer to employ all the elements of the composition in substantially the proportionsnamed but such limits, though affording the best results, may be varied or eitceeded somewhat and still ohtain favorable results under skillful manipulation, and all such modifications employing the elements substantially as herein described in about the proportions set forth I consider as coming within my invention and claim.

I claim as my invention The composition herein described for treating dehydrated gypsum, consisting substantially of thefollowing elements: water, alum, oxalic acid, aniline-blue, and sulphuric acid, in about the. proportions set forth.

In testimony whereofl have hereunto setmy hand.

RAPHAEL JOSIA.

Witnesses: G UlDO PANTALIONY, R. H. WHrr'rLEsnv. 

